Direct transfer between credit cards is not possible.

A credit card is an overdraft tool. It is only used for card consumption and cannot be used for transfers, deposits, withdrawals and other services. If you insist on using it, you will have to pay handling fees and interest. If you need to transfer money by credit card, you can use one credit card to withdraw cash and repay it to another credit card, but this will incur corresponding cash withdrawal interest and handling fees.